text: Many single-cell analysis techniques require the isolation of individual cells. Methods currently used for single cell isolation include: Dielectrophoretic digital sorting, enzymatic digestion, FACS, hydrodynamic traps, laser capture microdissection, manual picking, microfluidics, micromanipulation, serial dilution, and Raman tweezers.
  Manual single cell picking is a method where cells in a suspension are viewed under a microscope, and individually picked using a micropipette. Raman tweezers is a technique where  Raman spectroscopy is combined with optical tweezers, which uses a laser beam to trap, and manipulate cells.
  The Dielectrophoretic digital sorting method utilizes a semiconductor controlled array of electrodes in a microfluidic chip to trap single cells in Dielectrophoretic (DEP) cages. Cell identification is ensured by the combination of fluorescent markers with image observation. Precision delivery is ensured by the semiconductor controlled motion of DEP cages in the flow cell.
  The development of hydrodynamic-based microfluidic biochips has been increasing over the years. In this technique, the cells or particles are trapped in a particular region for single cell analysis (SCA) usually without any application of external force fields such as optical, electrical, magnetic or acoustic. There is a need to explore the insights of SCA in the cell's natural state and development of these techniques is highly essential for that study. Researchers have highlighted the vast potential field that needs to be explored to develop biochip devices to suit market/researcher demands. Hydrodynamic microfluidics facilitates the development of passive lab-on-chip applications. A latest review gives an account of the recent advances in this field, along with their mechanisms, methods and applications.